What is called a hybrid vehicle that runs with drive force from at least one of an engine and a motor has conventionally been known. The hybrid vehicle selects the engine and/or the motor in accordance with a running state or the like of the vehicle, such that characteristics of each of the engine and motor are made use of In such a hybrid vehicle, there is a need for air-conditioning also while the engine is not operating.
Japanese Patent Laying-Open No. 09-076740 discloses a hybrid vehicle capable of cooling while the engine is not operating. The hybrid vehicle described in Japanese Patent Laying-Open No. 09-076740 includes a drive engine (engine) using fuel, a battery for running, a motor drive apparatus driving a motor with electric power charged in the battery, and a cooling apparatus driven by the electric power of the battery for running.
According to the hybrid vehicle described in this publication, the cooling apparatus is driven by the electric power of the battery for running. Therefore, cooling can be performed while the drive engine is not operating.
Meanwhile, as the engine is driven by burning the fuel, the hybrid vehicle still emits exhaust gas and requires a catalyst purifying the exhaust gas. In order for the catalyst to exhibit an effect to purify the exhaust gas, the catalyst should sufficiently be warm. For example, it has been known that warm-up for raising a temperature of the catalyst is necessary when the engine is started after a long non-operating state. During warm-up of the catalyst, the engine is controlled such that the exhaust gas in an amount that can be purified by the catalyst being warmed up is emitted. Here, the drive force generated in the engine is not used for running the vehicle, but the vehicle runs by using the drive force generated by the motor that receives power supply from the battery.
In the hybrid vehicle described in Japanese Patent Laying-Open No. 09-076740, however, electric power of the battery is consumed for driving the cooling apparatus while the engine is not operating. Accordingly, a state of charge of the battery may be lower than a state of charge necessary for running the vehicle with the motor. If the state of charge of the battery is lower than the state of charge necessary for running the vehicle with the motor, the engine should be driven by output necessary for running the vehicle even during warm-up of the catalyst. Therefore, the exhaust gas in an amount exceeding purifying capability of the catalyst being warmed up may be emitted.